TW202020491A - Back-light module - Google Patents

Abstract

A back-light module includes a substrate, a plurality of light-emitting devices, and an optical film. The light-emitting devices are disposed on the substrate. The light-emitting devices are arranged in a rectangular array along the X direction and the Y direction. The optical film is disposed on the light-emitting devices. The optical film includes a plurality of pyramid structures arranged in array. Each of the pyramid structures includes four bottom edges. An angle between one bottom edge and the X direction and an angle between another bottom edge and the Y direction are more than 0 degree and less than 45 degree.

Description

Backlight module

The invention relates to a backlight module, and particularly to a backlight module with a pyramid structure.

The existing liquid crystal display device uses a backlight module as a light source, and uses liquid crystal to control whether light can leave the liquid crystal display device. Generally speaking, the backlight module includes many light emitting elements. In order to distribute the light emitted by these light emitting elements more uniformly, a diffuser plate (Diffuser plate) is usually provided on these light emitting elements. The diffusion plate changes the path of the light emitted by the light emitting element through physical phenomena such as refraction, reflection and scattering. The light leaving the diffuser often contains a large angle of exit light. In other words, the diffuser has the function of amplifying the angle of the emitted light. However, the light utilization rate of the emitted light at a large angle is poor, and it is easy to make the brightness of the screen displayed by the display device insufficient.

The invention provides a backlight module, which can improve the problem of uneven distribution of light emitted by the light-emitting elements while maintaining light utilization.

An embodiment of the present invention provides a backlight module including a substrate, a plurality of light emitting elements, and an optical film. A plurality of light emitting elements are located on the substrate. The light emitting elements are arranged in a rectangular array along the direction X and the direction Y. The optical film is located on the light emitting element. The optical film includes an array of multiple pyramid structures. Each pyramid structure includes four bottom edges. The angle between one of the bottom edges and the direction X and the angle between the other bottom edge and the direction Y are greater than 0 degrees and less than 45 degrees.

Based on the above, the pyramid structure in the optical film can change the travel route of the light emitted by the light emitting element, thereby allowing the backlight module to emit light with even distribution.

In order to make the above-mentioned features and advantages of the present invention more obvious and understandable, the embodiments are specifically described below and described in detail in conjunction with the accompanying drawings.

FIG. 1A is a schematic cross-sectional view of a backlight module according to an embodiment of the invention. FIG. 1B is a schematic perspective view of a pyramid structure according to an embodiment of the invention.

Referring to FIG. 1A, the backlight module 10 includes a substrate 100, a plurality of light emitting elements 110, and an optical film 120. In this embodiment, the backlight module 10 further includes a reflective layer 130, a dichroic film 140, a color conversion layer 150, a first prism sheet 160, and a second prism sheet 170.

A plurality of light emitting elements 110 are located on the substrate 100. The light emitting element 110 is, for example, a Mini LED or other light source. The light emitting element 110 is, for example, a blue light emitting element or a white light emitting element. In this embodiment, the light-emitting element 110 is a blue light-emitting element as an example.

In this embodiment, the light emitting element 110 and the substrate 100 further have a reflective layer 130, but the invention is not limited thereto. In other embodiments, the substrate 100 itself has the function of reflecting light. Therefore, no additional reflective layer 130 is required.

1A and 1B, the optical film 120 is located on the light emitting element 110. The optical film 120 includes a plurality of pyramid structures 122 and a carrier 124 in an array. Each pyramid structure 122 includes a rectangular bottom surface B and four edges L1 to L4 connecting the rectangular bottom surface B. The rectangular bottom surface B includes four bottom edges B1~B4. In this embodiment, the rectangular bottom surface B of the pyramid structure 122 is a square, but the invention is not limited thereto. In this embodiment, the pyramid structure 122 is formed on the carrier plate 124, and the pyramid structure 122 and the carrier plate 124 may be integrally formed, but the invention is not limited thereto. The materials of the pyramid structure 122 and the carrier plate 124 include resin, polycarbonate (PC), polymethyl methacrylate (PMMA), or other suitable materials.

The spectroscopic film 140 is located on the optical film 120. FIG. 2 is a schematic diagram of transmittance of a spectroscopic film (for example, the spectroscopic film 140 of FIG. 1A) at different wavelengths according to an embodiment of the present invention. The vertical axis of FIG. 2 is the transmittance, and the horizontal axis is the wavelength of the light. The different line segments in FIG. 2 represent the light with different incident angles.

Please refer to FIG. 2, the transmittance of the dichroic film 140 will vary due to the incident angle of light and the wavelength of light. In this embodiment, the spectroscopic film 140 has a high transmittance for blue light (wavelength about 450 nm) with a small incident angle (for example, less than 50 degrees). The spectroscopic film 140 has relatively high reflectivity for blue light, green light (wavelength about 540 nm) and red light (wavelength about 630 nm) with a large incident angle.

Please refer to FIG. 1A, the pyramid structure 122 of the optical film 120 enables the light to have a more suitable light emitting angle. Therefore, the optical film 120 of this embodiment can increase the efficiency of the forward light of the dichroic film 140 compared with the conventional diffusion plate that significantly increases the light exit angle.

The color conversion layer 150 is located on the dichroic film 140. The color conversion layer 150 includes, for example, quantum dot material or fluorescent material. The color conversion layer 150 can convert the color of light. For example, after passing through the optical film 120 and the dichroic film 140, part of the light is converted into red light and/or green light or light with a wavelength greater than 500 nm by the color conversion layer 150. In this embodiment, the spectroscopic film 140 has a high reflectivity for red light and green light. Therefore, the red light and/or green light emitted by the color conversion layer 150 can be reflected by the dichroic film 140, thereby increasing the utilization rate of light.

The first prism sheet 160 is located on the color conversion layer 150. The second prism sheet 170 is located on the first prism sheet 160. In some embodiments, the extending direction of the prism structure on the first prism sheet 160 is orthogonal to the extending direction of the prism structure on the second prism sheet 170.

FIG. 3 is a schematic top view of a backlight module according to an embodiment of the invention. For convenience of description, FIG. 3 illustrates the substrate 100, the light emitting element 110, and the optical film 120, and other components are omitted. For the omitted components, reference may be made to the description of the embodiment in FIG. 1A, and details are not described herein again.

3 and 1B, the light emitting elements 110 of the backlight module 10 are arranged in a rectangular array along the direction X and the direction Y. The direction X is orthogonal to the direction Y. The angle α1 between one base B1 and the direction X of the pyramid structure 122 and the angle α2 between the other base B2 and the direction Y are greater than 0 degrees and less than 45 degrees. In this embodiment, the bottom edge B1 is parallel to the bottom edge B3, and the bottom edge B2 is parallel to the bottom edge B4. In other words, the bottom edges B1 and B3 each form an angle α1 with the direction X, and the bottom edges B2 and B4 both form an angle α2 with the direction Y.

In this embodiment, the pyramid structures 122 are arranged in a rectangular array along the direction D1 and the direction D2. The direction D1 is orthogonal to the direction D2. The direction D1 is parallel to the bottom sides B1, B3. The direction D2 is parallel to the bottom sides B2, B4.

Although in this embodiment, adjacent pyramid structures 122 are in contact with each other, the invention is not limited to this. In other embodiments, adjacent pyramid structures 122 are spaced apart.

Based on the above, the pyramid structure 122 can change the travel route of the light emitted by the light emitting element 110, thereby allowing the backlight module to emit light with even distribution.

4 is a schematic top view of a backlight module according to an embodiment of the invention. It must be noted here that the embodiment of FIG. 4 uses the element numbers and partial contents of the embodiment of FIG. 3, wherein the same or similar reference numerals are used to indicate the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, which will not be repeated here.

The main difference between the backlight module 10a of FIG. 4 and the backlight module 10 of FIG. 2 is that the pyramid structure 122 of the backlight module 10a is misaligned.

Please refer to FIG. 4, part of the pyramid structure 122 is misaligned. For example, the bottom edges B1, B3 of the misaligned pyramid structures 122 are not aligned with the bottom edges B1, B3 of the adjacent rows of pyramid structures 122.

Based on the above, the pyramid structure 122 can change the travel route of the light emitted by the light emitting element 110, thereby allowing the backlight module to emit light with even distribution.

5 is a schematic top view of an optical film according to an embodiment of the invention. It must be noted here that the embodiment of FIG. 5 uses the element numbers and partial contents of the embodiment of FIG. 4, wherein the same or similar reference numerals are used to indicate the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, which will not be repeated here.

Please refer to FIG. 5, the pyramid structure of the optical film 120a has more than one size. For example, the optical film 120a includes pyramid structures 122a and pyramid structures 122b with different sizes, wherein the bottom edge of the pyramid structure 122a is larger than the pyramid structure 122b, but the height dimension of the 122a is not limited to 122b.

Although in this embodiment, the optical film 120a includes pyramid structures of two sizes as an example, the invention is not limited thereto. In other embodiments, the optical film 120a includes a pyramid structure of more than three sizes.

6 is a schematic top view of an optical film according to an embodiment of the invention. It must be noted here that the embodiment of FIG. 6 uses the element numbers and partial contents of the embodiment of FIG. 5, wherein the same or similar reference numerals are used to indicate the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, which will not be repeated here.

The main difference between the optical film 120b of FIG. 6 and the optical film 120a of FIG. 5 is that the arrangement of the pyramid structure in the optical film 120b is different from the arrangement of the pyramid structure in the optical film 120a.

In the optical film 120a of FIG. 5, two pyramid structures 122a having larger sizes are adjacent to each other. In the optical film 120b of FIG. 6, the two pyramid structures 122a with a larger size are separated by the pyramid structure 122b with a smaller size.

Although FIG. 5 and FIG. 6 propose two arrangements of pyramid structures, the invention is not limited thereto. The arrangement of the pyramid structure can be determined according to actual needs. In addition, the number of pyramid structures in the optical film can also be determined according to actual needs.

7 is a schematic top view of a backlight module according to an embodiment of the invention. It must be noted here that the embodiment of FIG. 7 uses the element numbers and partial contents of the embodiment of FIG. 3, wherein the same or similar reference numerals are used to indicate the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, which will not be repeated here. For convenience of description, FIG. 7 illustrates one of the pyramid structures 122 in the substrate 100, the light emitting element 110, and the optical film 120, and omitting other components. For the omitted components, reference may be made to the description of the embodiment in FIG. 1A, and details are not described herein again.

7 and 1B, in the backlight module 10b, the ratio of the pitch G1 (pitch) of the light emitting element 110 in the direction X to the pitch G2 of the light emitting element in the direction Y is 1:1.

The pyramid structure 122 includes a rectangular bottom surface B and four edges L1 to L4 connecting the rectangular bottom surface B. The vertical projections of the edges L1 to L4 on the substrate 100 extend along the first to fourth directions E1 to E4, respectively. The vertical projection of one edge L1 on the substrate 100 extends along the first direction E1, and the angle β1 between the first direction E1 and the direction Y is 11 degrees to 31 degrees. In this embodiment, β1 is preferably 21 degrees.

In this embodiment, the optical film 120 refracts and reflects the light emitted by the light emitting element 110, and forms a plurality of virtual light sources DM1~DM4. Each of the four virtual light sources DM1 to DM4 corresponds to a light emitting element 110. Viewed in the direction perpendicular to the substrate 100, the connection between the virtual light source DM1 and the light emitting element 110 extends along the direction T1, which is between the first direction E1 and the second direction E2. For example, the angle between the direction T1 and the first direction E1 is equal to the angle between the direction T1 and the second direction E2, but the invention is not limited thereto. Viewed in the direction perpendicular to the substrate 100, the connection line of the virtual light source DM2 and the light emitting element 110 extends along the direction T2, and the direction T2 is between the second direction E2 and the third direction E3. For example, the angle between the direction T2 and the second direction E2 is equal to the angle between the direction T2 and the third direction E3, but the invention is not limited thereto. Viewed in the direction perpendicular to the substrate 100, the connection between the virtual light source DM3 and the light emitting element 110 extends along the direction T3, which is between the third direction E3 and the fourth direction E4. For example, the angle between the direction T3 and the third direction E3 is equal to the angle between the direction T3 and the fourth direction E4, but the invention is not limited thereto. Viewed in the direction perpendicular to the substrate 100, the connection between the virtual light source DM4 and the light emitting element 110 extends along the direction T4, which is between the fourth direction E4 and the first direction E1. For example, the angle between the direction T4 and the fourth direction E4 is equal to the angle between the direction T4 and the first direction E1, but the invention is not limited thereto.

Based on the above, the optical film 120 refracts the light emitted by the light emitting element 110 and forms a plurality of virtual light sources DM1 to DM4. Therefore, the backlight module 10b can emit uniformly distributed light.

8 is a schematic top view of a backlight module according to an embodiment of the invention. It must be noted here that the embodiment of FIG. 8 uses the element numbers and partial contents of the embodiment of FIG. 7, wherein the same or similar reference numerals are used to indicate the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, which will not be repeated here. For convenience of description, FIG. 8 illustrates one of the pyramid structures 122 in the substrate 100, the light emitting element 110, and the optical film 120, and omitting other components. For the omitted components, reference may be made to the description of the embodiment in FIG. 1A, and details are not described herein again.

The main difference between the backlight module 10c of FIG. 8 and the backlight module 10b of FIG. 7 is that in the backlight module 10c, the pitch G1 of the light emitting element 110 in the direction X is greater than the pitch G2 of the light emitting element 110 in the direction Y.

Referring to FIG. 8, the ratio of the pitch G1 of the light emitting element 110 in the direction X to the pitch G2 of the light emitting element 110 in the direction Y is 2:1.

The angle β1 between the first direction E1 and the direction Y is 11 degrees to 31 degrees. In this embodiment, β1 is preferably 16 degrees.

Based on the above, the optical film 120 refracts the light emitted by the light emitting element 110 and forms a plurality of virtual light sources DM1 to DM4. Therefore, the backlight module 10c can emit uniformly distributed light.

9 is a schematic top view of a backlight module according to an embodiment of the invention. It must be noted here that the embodiment of FIG. 9 uses the element numbers and partial contents of the embodiment of FIG. 7, wherein the same or similar reference numerals are used to indicate the same or similar elements, and the description of the same technical content is omitted. For the description of the omitted parts, reference may be made to the foregoing embodiments, which will not be repeated here. For convenience of description, FIG. 9 illustrates one of the pyramid structures 122 of the substrate 100, the light emitting element 110, and the optical film 120, and omitting other components. For the omitted components, reference may be made to the description of the embodiment in FIG. 1A, and details are not described herein again.

The main difference between the backlight module 10d of FIG. 9 and the backlight module 10b of FIG. 7 is that in the backlight module 10d, the pitch G1 of the light emitting element 110 in the direction X is greater than the pitch G2 of the light emitting element 110 in the direction Y.

9, the ratio of the pitch G1 of the light emitting element 110 in the direction X to the pitch G2 of the light emitting element 110 in the direction Y is 3:1.

The angle β1 between the first direction E1 and the direction Y is 11 degrees to 31 degrees. In this embodiment, β1 is preferably 11 degrees.

Based on the above, the optical film 120 refracts the light emitted by the light emitting element 110 and forms a plurality of virtual light sources DM1 to DM4. Therefore, the backlight module 10d can emit uniformly distributed light.

In summary, the optical film refracts the light emitted by the light emitting element and forms multiple virtual light sources. Therefore, the backlight module can emit uniformly distributed light. In addition, compared to using a traditional diffuser that significantly increases the angle of light exit, light passing through the optical film can easily penetrate the dichroic film, thereby increasing light utilization.

Although the present invention has been disclosed as above with the embodiments, it is not intended to limit the present invention. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present invention. The scope of protection of the present invention shall be subject to the scope defined in the appended patent application.

10.10a~10d: Backlight module 100: substrate 110: light emitting elements 120, 120a, 120b: optical films 122, 122a, 122b: pyramid structure 124: carrier board 130: reflective layer 140: spectroscopic film 150: color conversion layer 160 : First prism sheet 170: Second prism sheet B: Bottom surfaces B1~B4: Bottom edges D1, D2, E1~E4, T1~T4, X, Y: Direction DM1~DM4: Virtual light sources G1, G2: Pitch L1 ~L4: Edge α1, α2, β1: Angle

FIG. 1A is a schematic cross-sectional view of a backlight module according to an embodiment of the invention. FIG. 1B is a schematic perspective view of a pyramid structure according to an embodiment of the invention. 2 is a schematic diagram of transmittance of a spectroscopic film at different wavelengths according to an embodiment of the invention. 3 is a schematic top view of a backlight module according to an embodiment of the invention. 4 is a schematic top view of a backlight module according to an embodiment of the invention. 5 is a schematic top view of an optical film according to an embodiment of the invention. 6 is a schematic top view of an optical film according to an embodiment of the invention. 7 is a schematic top view of a backlight module according to an embodiment of the invention. 8 is a schematic top view of a backlight module according to an embodiment of the invention. 9 is a schematic top view of a backlight module according to an embodiment of the invention.

10: Backlight module

100: substrate

110: light emitting element

120: Optical film

122: pyramid structure

B1~B4: bottom edge

D1, D2, X, Y: direction

α 1, α 2: Angle

Claims (10)

A backlight module includes: a substrate; a plurality of light-emitting elements on the substrate, and the light-emitting elements are arranged in a rectangular array along direction X and direction Y; and an optical film on the light-emitting elements, The optical film includes a plurality of pyramid structures of the array, each of the pyramid structures includes four bottom edges, an angle between one bottom edge and the direction X and an angle between the other bottom edge and the direction Y are greater than 0 Degrees and less than 45 degrees. The backlight module according to item 1 of the patent application scope, wherein each of the pyramid structures includes a rectangular bottom surface and four edges connecting the rectangular bottom surface, wherein a vertical projection of one edge on the substrate is along a first direction Extending, the angle between the first direction and the direction Y is 11 degrees to 31 degrees. The backlight module as described in item 2 of the patent application range, wherein the ratio of the pitch of the light emitting elements in the direction X to the pitch of the light emitting elements in the direction Y is 1:1. The backlight module as described in item 2 of the patent application range, wherein the pitch of the light emitting elements in the direction X is greater than the pitch of the light emitting elements in the direction Y. The backlight module as described in item 4 of the patent application range, wherein the ratio of the pitch of the light emitting elements in the direction X to the pitch of the light emitting elements in the direction Y is 2:1. The backlight module as described in item 4 of the patent application range, wherein the pitch ratio of the light emitting elements in the direction X to the pitch of the light emitting elements in the direction Y is 3:1. The backlight module as described in item 1 of the patent application scope, wherein the pyramid structures have more than one size. The backlight module as described in item 1 of the patent application scope, wherein the pyramid structures are arranged in a misaligned manner. The backlight module as described in item 1 of the patent application scope, wherein the materials of the pyramid structures include resin, polycarbonate, or polymethyl methacrylate. The backlight module as described in item 1 of the patent application scope further includes: a dichroic film on the optical film; and a color conversion layer on the dichroic film.

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